Contactless chip cards increasingly replace chip cards provided with contacts. The reason therefor is particularly due to the fact that contactless chip cards allow an easier handling, have a more robust construction and are, thus, less susceptible to failure, and they offer a number of interesting new possibilities as far as their use is concerned, as they do not have to be inserted into a reading device.
It is generally known that contactless chip cards comprise a loop conductor or antenna provided in the chip card, by means of which the chip likewise provided in the chip card can communicate with the world outside. For this purpose, the loop conductor has to be connected during the production of the contactless chip card with the contacts of the chip or, respectively, the corresponding module. For achieving this electrical connection between the loop conductor and the chip, a plurality of methods have already been proposed, whereby particularly the following methods were successful.
FIG. 10 illustrates the principle as to how, according to the prior art, an electrical connection between a chip module 1 and a loop conductor 4 is typically produced.
A chip module 1, in the interior of which a non-illustrated chip is provided, comprises externally accessible contacts 2 which are connected with the actual contacts of the chip, for example, by means of a soldering, gluing or wire bonding process. Reference number 3 designates contact terminals producing, by means of an electrical conductor 5, an electrical connection to the loop conductor 4 disposed on a chip card body 6. In order to eventually obtain a contact between the loop conductor 4 and the chip, the contacts 2 have to be connected with the contact terminals 3 in an electrically conductive fashion. For this purpose, module 1 is placed onto the contact terminals 3 by means of a tool, namely with the side provided with the contacts.
Another possibility resides in placing the chip 15 as such, i.e. not in the form of a module, but “naked”, onto the contact terminals 3, which is illustrated in FIG. 10a. By using this modification, the chip 15 has to be placed onto the contact terminals 3 with its “active side”, i.e. the side bearing the bond pads 13. For this purpose, the chip must be “flipped”, which requires the gripping of the chip 15 from the wafer or carrier substrate twice.
FIG. 11 illustrates another possibility, namely as to how, according to the prior art, an electrical connection between a chip 15 and a loop conductor 4 can be produced by means of a wire bonding process.
In order to achieve, in this case, a contact between the loop conductor 4 and the chip 15, the chip is applied onto the chip card body 6, and the bond pads 13 are connected with the contact terminals 3 by means of wire bonds in an electrically conductive fashion. It can be seen that, in accordance with this solution, the chip 15 no longer has to be flipped. However, the wire joints 34 produced by the wire bonding require a larger overall construction height of the chip card and, moreover, have to be protected by a solid protection layer.
Another type of contact is known from German patent DE 196 09 636 C1. According to the solution described therein, a chip module is brought into a recess of the chip card body such that the contacts provided on the surface of the module have even ends with path conductors on the body surface, so that a contact between the loop conductor and the contacts of the module can be achieved. A drawback in this embodiment resides in that the depth of the recess must be dimensioned with extreme exactness to as to allow the plane ending of both contacts.